An object of typical sonar and radar systems is to localize a target of interest. Localization typically comprises determining a range and bearing to the target of interest Strong interferers can mask signals representing these targets. Examples of interferers include surface shipping traffic for sonar systems and jammers for radar systems.
To suppress interference, systems have utilized arrays of sensor elements. Given knowledge of the exact phase shifts with respect to the signals received by the elements of the array, notches can be formed in beam patterns and steered in the direction of the interferer to suppress, and even cancel the interfering energy. In practice, these phase shifts are estimated. However, factors such as array motion, uncertainty of the location of elements in the array, uncertainty of the orientation of the array, and environmental affects such as multipath phenomena, produce errors in phase shift estimations.
Errors in phase shift estimation can result in notches being formed that are too wide, thus suppressing energy other than interference energy. This is of particular concern when the interferer is spatially close enough to the target of interest such that the notch actually suppresses the desired signal provided by the target of interest. Also, errors in the phase shift estimation can result in notches that are not steered to the proper direction. An improved scheme for suppressing interference is desired.